Aberrant IL-6 expression in SLE. SLE is an autoimmune disease of uncertain, etiology. Our long-range goal is identifying factors that predispose to SLE and contribute to its skewed immune regulation. Such a factor may be IL-6, that is normally under tight gene regulation, but is constitutively expressed in SLE. IL-6 over-expression may result from mutations in gene control regions. Preliminary data on elevated incidence of allelic restriction fragments in IL-6 gene of SLE patients and high IL- 6 mRNA levels in allelic individuals' supports this possibility. The allelic fragments were 200 bp larger, and mapped to an AT-rich area in the 3' flanking region of the gene. Our hypothesis is that altered fragments in control regions of the IL-6 gene are associated with SLE, and that they contribute to the aberrant IL-6 expression. We propose to establish the association of IL-6 gene allelic, altered- size restriction fragments with SLE, by expanding our screening for RFLP and SSCP to statistically significant numbers of patients and controls. Based on our results, and for practical reasons, SSCP analysis will be limited to 2' main regulatory regions of the gene: the proximal 500 bp 5'promoter region, and a 1.3 kb 3'segment spanning from within exon V to beyond the 2nd polydenylation signal. We will identify predominant, disease-associated variations in 5'and 3' control regions of the IL-6 gene, sequence them, and evaluate codistribution with factors pathogenic in SLE (DR/DQ alleles, autoantibodies, and high IL-6 mRNA levels)and kidney disease. We will identify transcriptional or post transcriptional events that up-regulate IL-6 in SLE, evaluate their possible segregation with discrete IL-6 alleles, and directly study the effects of the allelic regions on deregulation of IL-6 gene expression in cells transfected with CAT reporter gene constructs with normal and mutated control regions. If IL-6 gene mutations contribute to gene deregulation, and if, with other genetic factors, they confer susceptibility, to SLE, these studies should clarify basic aspects of the etiology of this complex disease, provide tools for pre-clinical evaluation of disease risks, and offer new approaches for targeted therapy.